Work endeavors frequently involve moving a variety of objects or tools from one location to another. Such objects can often be too large, quantitative, and/or heavy for one or more persons to move without assistance of a cart or dolly. As a result, a variety of such carts have been developed for loading and moving articles. Such carts, however, require a large storage space due to their required size for hauling large loads. Moreover, the size of such carts often precludes conveniently loading them into a transport vehicle for use at distant work sites. In order to provide a more transportable and storable device, the prior art provides a variety of folding and collapsible carts.
U.S. Pat. No. 1,970,727 discloses a leaf incinerator and dump cart which can be knocked down and disassembled with all of its parts laid in a compact arrangement for a crating operation. Similarly, U.S. Pat. No. 5,318,315 discloses a portable wheel cart which must also be disassembled in order to effectuate storage. U.S. Pat. No. 4,824,137 discloses a cart with a collapsible inner basket comprised of removable side panels mounted onto a wheeled frame and a removable top frame for securing the panels in place. Complete disassembly of these carts, however, is required for storage. Such disassembly is inconvenient and time consuming as the cart must be completely reassembled at the distant location.
U.S. Pat. No. 4,253,677 discloses a folding utility cart with side panels which can be removed and slidably attached to the bottom floor panel of the cart for flat storage. This cart also requires partial disassembly of the component parts in order to effectuate folding of the cart.
Still other disclosures provide a collapsible bin or utility area. For instance, U.S. Pat. Nos. 4,266,791 and 4,624,467 disclose foldable utility carts having hinged sidewalls which fold to lie flat against the floor of the cart. U.S. Pat. No. 5,080,387 discloses a collapsible utility carrier with hinged front and rear members which fold to lie flat against horizontal cross members. U.S. Pat. No. 4,669,743 discloses a collapsible cart whereby the floor hinges upward to fit between the vertically oriented sidewalls which are drawn together. Alternatively, U.S. Pat. No. 4,957,306 discloses a leaf carrying wagon whereby the floor and/or carrying bin of the cart hinges back upon itself for transport and storage. U.S. Pat. Nos. 4,635,956 and 4,826,202 disclose carts having a collapsible storage basket which is mounted on a frame. The basket side panels are hinged in the middle and fold inwards to achieve a folded container form. These latter carts, while collapsible in some respect, do not provide upper and lower working surfaces or shelves which would allow a user to conveniently load and stack items on two different levels.
Accordingly, what is needed in the field is a foldable or collapsible cart which provides multiple working shelves, with the uppermost shelf capable of being elevated to a working position. In the storage position, the upper shelf would thereby lie flat upon the lower shelf with an extendable connection between the two shelves. A conveniently-releasable locking mechanism should also be provided for controllable raising and lowering the upper shelf. The upper shelf, or a portion thereof, might also be removable in order to allow for top loading of larger items.